Process of making an adhesive and the product thereof



N Drawing.

Patented Dec. 8, 1931 UNITED STATES PATENT OFFICE HARRY I. BANKS AND GLENN DAVIDSON, OI SEATTLE, WASHINGTON, ASBIGNOBB IO I. F. LA'UCKS INC 0] SEATTIE, WASHINGTON, A CORPORATION OF WASHINGTON PROCESS OF MAKING AN ADHESIVE AND TEE PRODUCT TI Our invention relates to the process of making an adhesive and the product thereof. More particularly, our invention relates to the process of making an improved adhesive 5 and to the product thereof by combining milk casein and soya bean flour, or like vegetable protein, such as the protein of the peanut as it is contained in flour made from peanut cake or meal, and the protein in flour made from cottonseed cake or meal, and similar protein containing meals which when used in the same manner as is described for soya bean flour herein, react in similar manner and produce similar efiects in the finished adhesive. Our invention will be described in relation to the particular problems obtaining in the manufacture of a suitable adhesive for ply wood panels. However, while our invention will be thus described in connection with the particular problems of a particular use, nevertheless it is not to be deemed as limited to any such specific use, but is applicable to all uses where like problems and conditions obtain,-for example, in the manufacture of sizings, calcimines, etc., where an efficient and relatively inexpensive adhesive is desired.

One of the definite conditions to be satisfied in providing an adhesive for ply woods is the providing of an adhesive which is charnotarized by the property of maintaining the glue on the glue line in proper condition to form a bond. It will be remembered that in the making of ply wood after applyin the adhesive to the cores or faces and assem ling of the same, the assembled panel is of necessity allowed to stand for a period of time because of plant requirements, until a full rack ofpanels is assembled and ready for the application of pressure. The problem is to maintain the glue at such consistency that it will be held on the glue line in a proper degree of thickness to form said bond when pressure is applied.

Ordinary cold process glues are applied to the veneer in the form' of a sirupy colloidal Application filed August 10, 1926. serial No. 49,442.

solution of the adhesive materials. Under ideal conditions, a certain time, dependent upon the nature of the glue, wood, etc., should be allowed to elapse before the two surfaces to be attached should be brought into intimate contact by means of pressure. This period of time is referred to in literature concerning glueing as the time of assembly. During this time of assembly, the glue changes from a sirupy solution to a more or less gelatinous film upon the surface of the wood. This is due, among other things, to loss of moisture from the glue to the wood upon which it is spread and to surrounding air. Now if pressure is applied before the glue has attained this condition of a elatinous film, i. e., while it is still in its original sirupy condition, the glue is comparatively easily forced out of the joint, e. g., in veneering out at the edges of the panel. It is also under the above conditions relatively easily absorbed deeply into the pores of the wood, too far away from the glue line to be of service in enhancing the strength of the bond.

The above conditions lead to what is termed a starved joint. A primary object of our invention is to provide a glue which will overcome to a certain extent this difficulty of starved joints encountered in veneering practice, where it is not possible to control the time of assembly. That is, racks of panels must in practice be placed under pressure as rapidly as they can be assembled. Accordingly, the time which ordinarily elapses during the assembling and placing under pressure of a rack of panels gives a sufiicient time of assembly for the bottom panels in the rack,

but frequently an insuflicient time for the top panels, i. e., the last panels assembled. It is of course understood that the rack as a whole cannot be allowed to stand to give sufiicient time of assembly for the top panels, lest the glue on the bottom panels becomes entirely dry. Ordinarily milk casein formulae give a-slrup free from colloidal adsorbent with milk casein material and accordingly starved 'oint trouble is fr uently aggravated with-t ese glues. We have ound it possible, however, to at ly reduce the tendency toward starved oints lues by admixing with the milk casein, soyafiiean flour. The soya bean flour, being more diflicultly dispersed than the milk casein, will partly disperse and partly remain as a flocculent adsorbent material floating in a milk casein dispersion when the mixture of milk casein and soya bean flour is treated with the ordinary reagents hereinafter mentioned for producing milk casein dispersion. This partlally dispersed soya bean flour contributes to a certain extent in and of itself to strength of the bond formed between two surfaces of wood, but what is of gerater importance, it appears to act as a sponge and prevent the escape of the glue from the glue line in cases where-pressur is applied before sufiicient t1me of assembly haselapsed as outlined above.

The termpartially dispersed soya bean flour is used to designate the flour when part thereof has been broken up and subdivided to a degree of fineness required by colloidal dispersion, and part thereof still remains a flocculent adsorbent material. The term dispersion is used here in the recognized sense developed in colloidal chemistry. Colloids or dispersed systems, can be formed in two different ways: (1) by subdividing coarse materials into fine particles, or (2) by gathering smaller particles or molecules or atoms together to a particle of the size of a colloidal particle. The first class we call dispersion methods and the second class condensive methods. -Hence colloidal chemistry deals with the behavior and properties of matter in the colloidal condition', which, as we have seen, means .a certain very fine state of subdivision, there being no sharp limitations to the size of particles in colloidal dispersion.

" In connection with the problem of maintaining glue on the glue line, the following condition'is to be noted. In the manufacture of ply wood, the plant may have the material from one log which is particularly free from resin, while the material from the next log may be Very resinous. Therefore, there is this mixed product to be dealt with in'manufacturing plywood that cannot be foreseen. The resin seems to form a more or less smooth hard surface or coating, and this coating or film, so far as we are able to determine, seems to provide a body as it were which prevents the glue from gripping or taking hold of the fiber of the wood. The alkaline portion of the glue seems to cut this film and make it .possible for the glue to act upon the fiber of the wood. Therefore, the importance of having a sufliciently active alkaline portion 7 present in the glue is manifest; However, if

such excess active alkaline agent is present in milk casein glue, wherethe said glue is to be applied to materials relatively free from resin, then such alkaline agent seems to lower the adhesive properties of the milk casein element. v

This results from excessive netration in the wood of highly alkaline ue. Our aim is to providean adhesive w ich overcomes these objections and is applicable to use upon both types of wood, that which is characterized by havingexcessive resin present and that which is relative] free from resin.

When the chemica s, that are usually added to milk casein to form glues, are used with a mixture of milk casein and soya bean flour, a certain amount of dispersion takes place, both of themilk casein and soya bean flour, or of the proteins of the soya bean. Our experience is thatalkalinity chemically is necessary for this dispersion of the soya bean material. With most of the ordinary mixtures added to milk casein to form lue, alkalinity is developed; for example, e plus either sodium fluoride, sodium phosphate sodium borate, sodium silicate, and the like in water, form caustic soda,-these being the usual chemicals added to milk casein glues, i. e. these are the ordinary reagents for producing milk casein dispersion. The milk casein, however, seems to have a further effect of acting hke a protecting colloid on the partially dispersed soya bea terial. For example, partially dispersed soya bean flour, while it has a certain amount of adhesiveness, does not form a smooth. easily spread glue. Be it noted by smooth is meant that the mass is free from lumps. Very finely ground milk casein is diflicult to disperse in a liquid, 'be'cause it is difiicult to completely wet. The same is true in some instances of soya beaiiflour. Soya bean flour nma- I ma be heat-treated, however, if desired,

an among other results an increased ease of wettingmay be provided of a soya bean flour before it is heat treated. On the other hand, more coarsely ground milk casein is comparatively easy to wet and this is also true of highly heat treated soya bean flour. Therefore, if it is desired to use finely ground milk casein, a ready dispersion may be attained by mixing with the milk casein a proper proportion of soya bean flour, which has received a high degree of heat treatment. Coarse casein may be defined, for purposes herein, as casein which would not pass a thirty-inesh screen, while fine casein may be defined as casein which would pass a sixty-mesh screen. Also, if it is desired in a certain formula to use soya bean flour, which has had little if any heat treatment, a ready dispersion may be greatly facilitated by addition of a proper proportion of coarsely ground milk casein. As respects the spreadibility of the glue, it

should be noted that this feature is also an essential characteristic of a ly when used for ply wood. y th1s is meant that it may be mechanically a plied by the roller means to the core or to t e face members constituting the ply wood structure. By addin milk casein to the soya bean flour, the nnxture smooths out, and a great improvement is effected.

It is of course possible to treat soya bean flour without any such mixture of milk casein, so as to form a smooth easily spread glue,

and the addition of milk casein, therefore, be

it particularly noted, is only one means of effecting the desired result of smoothness and spreadability.

Furthermore, our experience shows that the mixture of partially dispersed soya bean material makes an improvement on said milk casein formulae, especially such as tend to give a thin glue, in that the soya bean flour functions as an adsorbent. Of course, inert adsorbent materials may be added to such thin milk casein to function as an adsorbent, as is sometimes done by adding socalled sander-dust, i. e., wood flour. By adding to the milk casein a partially dispersed soya bean flour, which, even though partially dispersed, has. in itself considerable adhesiveness, a great improvement is effected over simply/the inert non-adhesive adsorbent. The excessive penetration of highly alkaline glue, hereinabove referred to. may be off-set by sponge action of partially dispersed soya bean flour. The soya bean flour, however, does not prevent the alkaline portion of the glue cutting through the resin film on the surface.

' tein thus serves a double purpose. First, it

The soya bean flour or like vegetable proacts as an adsorbent material for the milk casein, and, second, it has adhesive qualities in and of itself.

The proportions of each ingredient, milk casein, soya bean flour, or like protein material. may vary within wide limits. Where soya bean flour is desired to be the principal ingredient, only enough milk casein is used to form a smooth glue, the milk casein acting as a protecting colloid. On the other hand, where it is desired to provide a glue which overcomes the objections above noted,

which obtain in milk casein formulae, by furnishing an adsorbent property, a small amount of soya bean flour or like vegetable protein material may be added. The proportions may vary in the range from onetenth of one part milk casein to one part of soya bean flour to ten parts of milk casein to.

%lue, particular-' lows.

For ply wood purposes:

Parts Soya bean fiour 150 Coarse milk casein 30 Lime 50 Resin 5O Caustic soda 30 Sodium silicate 90 Potassium permanganate 10 Water 790 2 Soya bean flour 15 Coarse milk casein 5O Magnesia 90 Caustic soda- 30 Trisodium phosphate 20 Water 600 3 Fine milk casein 8O Soya bean flour 2O Lime 15 Sodium fluoride a 12 \Vater to bring to proper consistency.

For sizing Parts Soya bean flour 35 Milk casein 5 Sodium fluoride 2 Lime 2 Water to proper consistency.

We have found that respecting soya bean flour or flour ground from soya bean cake, which is the residue remaining from the soya bean after a'portion or all of the oil has been removed, certain new and useful properties are imparted to the soya bean flour by means of heat treatment of the same before 1t is admixed with the chemicals commonly use This part of our disclosure constitutes the sub ect matter of a co-pending application, Serial No. 116.010.

We believe that such heat treatment causes partial coagulation of the protein material, and, 1n fact, it is stated by other investigators of soya bean material that certain constituents of the soya bean protein are coagulated by heat, the amount of coagulation being dependent on the degree of heat and the dura tion of the heat.

It will be understood that in the milling of soya beans to extract oil and make pressed cake, a certain amount of'heat is used. The heating is in genera by two diflerent methods. In making the so-called round cake or cartwheel cake, the heating is with live steam on the crushed beans for about one minute or at least for a very short period of time. ln making the flat cake known as .English style cake which is further exemplified as the standard product of the Anglo Chinese Eastern Trading (30. it is understood, the heating is accomplished by cooking the beans at a'temperature slightly below the boiling point water, (about 200 Fahrenheit), for an hour or more. In each The so-called cartwheel cake of coinmerce is very irregular in quality and condition of protein and is quite liable to mold and still further impair its usefulness for adhesive purposes. This tendency to deteri-' orate in storage and during transportation is due in part at least to the'high moisture content to 17%). The English style cake, as described about, or the meal obtained by coarse grinding of same, however, is quite uniform in condition of the protein content, the moisture content is lower, being eight to tenper cent and 011 content approximately six per cent. This cake keeps well,

in storagefand during transportation. When cake is hereinafter noted in this appllcation we refer to this English style pressed soya bean cake.

At times we find even this cake to have a degree of non-uniformity in condition'of the protein due to a degree of heating of-th beans or cake which is greater or less than the average. We find for example some cake that is in a'condition that we call raw;

it is to be understood, however, that what we term raw cake has nevertheless been subjected to the action of heat, and the protein constituents, as compared to those of raw beans, has, of course, been much changed or coagulated. However, we term flour from such cake raw flour to distinguish it from other flours which, as we can determine by tests, have been subjected to greater degrees of heat.

We have found that adhesives-mad? from whatwe term raw flour are quite lnferior.

When the dry glue powder composed of such flour as a base, together with the other in- .f gredients comprising the formula, is mixed with water the resulting glue or adhesive is very lumpy and hard or impossible to mix uniformly. At the same time it has a great tendency to foam considerably in mechanlcal mixers and Spreaders. Foam, of' course,

ruins glue or at .least greatly impairs the strength of the bond.

We have determined that if we start with raw flour which has the extremely undesirable properties described above and subject amount.

such flour to best, we then correct these (is-- fects and produce a flour which, when mixed in accordance with our regular formulaeset forth in the above named applications, will make a good. adhesive or glue. The amount of heating to which the raw flour is sub 'ected in such a, process depends pon the ag e of heating which the cake, romwhi cfh" the flour is made, has previously receivd As this-necessary heat treatment. varies somewhat in amount or degree with different lots or shipments of flour received, we have cor 1 trived certain tests which we apply to the flour to determine its degree of rawness. We then adjust the heattreatment, both as to degree of temperature and length of time,

so as to roduce flour containing protein coa ulate to the proper degree.

One of the .tests is what we term the absorption test: Twenty (20) grams of flour are mixed with twenty (20) gramsof water and the mass kneaded into a small pat. This pat'when so made must not be too sticky, but at the same time should have an appreciable degree of stickiness. As a measure of this stickiness we would say that it is just sufiicient to pick up a .fifty grams brass weight having an area of one square inch but it should not'hold suehyeight for more than a few seconds. Also'the mass is made into a round ball and dropped from a height of three feet to a wood surface. It should not flatten out to any extent but should keep its spherical shape and be practically on the point of showing a slight rebound. If the pat as above prepared will not pick up the weight, but is crumbly and mealy, then it is not raw enough for our purposes, i. e., it has been heated too much. If it is too sticky,

then it is too raw. The pat test determines all heat up to the time of the expression of the oil and drying and milling and processing inthe presence, of live steam. If at the end of v the processing, the pat test shows that it is too raw, then itis. reheated to the requisite We are also able to judge as to the amount of heating to which a flour has been subjected and the further amount required by the smell, although this characteristic is very difficult to describe in words. The flour used in making the absorption or pat test above described has the green odor probably best described as suggesting new mown alfalfa hay. Heating makes this odor less pronounced and imparts a cooked odor.

Further, of course, as noted above, we are able to determine the state of the flour by the action ofthe glue'mixture, made with the flour as a base, in the mechanical'or hand mixers, i. e., whether it foams or not. If it foams considerably,,then it is too raw, and more heat is applied.

As a specific example setting forth the steps issues of the process of making and mixing anadhesive com osition:

Mix dry 1n suitable batch mixer. I I

In suitable mixer place 600 parts of water,

.add the mixture of dry ingredients listed above. Stir until well mixed. Dissolve 30 parts of caustic soda in 60 parts of water and add to the glue mixture while stirring. Stir for 10 minutes, add 90 parts of sodium silicate and 130 parts of water.' Stir for five minutes. The adhesive is now ready for spreading in mechanical spreader on plywood. The characteristics of this adhesive,

the directions for mixing of which are given as one example, are described heretofore.

The adhesive embodying our invention is characterized by having the property of maintaining the glue on the glue line. Furthermore, the product is characterized by greater smoothness and spreadability and greater water resistance. Furthermore, the product thus provided has all the advantageous properties of strai ht milk casein formulae adhesive, and at t e same time overcomes the disadvantages inherent in milk casein glue, and said product is characterized at the same time by being much less expensive to manufacture than said milk casein adhesive. I

We claim:

1. In the method of making an adhesive, the step of adding to dispersed milk casein an adsorbent partially dispersed vegetable protein containing matter in the presence of water.

2. In the method of making an adhesive, the step of adding to milk casein dispersed in an aqueous alkaline medium a vegetable protein containing matter.

3. In the method of making an adhesive,

the step of adding to milkcasein dispersed in an aqueous alkaline medium soya bean flour.

4. In the method of making an adhesive,

the step of partially dispersing vegetable protein containing matter in the presence of milk casein and water.

5. In the method of making an adhesive, the step of partially dispersing soya bean flour in the presence of dispersed milk casein and water.

6. In the method of making an adhesive, the step of heating soya bean flour and subsequently partially dispersing the same in an alkaline medium in the presence of dispersed milk casein.

7. In the method of making an adhesive, the steps of mixing soya bean flour, coarse milk casein, resin and potassium permanganate; adding water to the mixture thus sive embodying milk casein formed stirring until well mixed; stirring in sodium silicate and water;

.8. In the method of making adhesive, th'e 'ste of adding soya bean flour to milk casein mt e presence of ime andwater and an alka'"v jin'caustlc soda d1ssolved in water and stirring line metal salt which will form caustic soda in the presence of lime.

9. As an article of manufacture, an adhetein containing matter, and water.

10. As an article of manufacture, an adhesive embodying milk casein, soya bean flour, and water. 7

11. As an article of manufacture, an adhe- .sive embodying milk casein dispersed in an aqueous alkaline medium, and heat treated soya bean flour.

12. As 'an article of manufacture, an adhesive embodying milk casein dispersed in an aqueous alkaline medium, and steam treated' soya bean flour. I

, 13. As an article of manufacture, an adhesive embodying-milk casein and vegetable protein containing matter, which constitu- ,ents are intermixed in the presence of water in the range of proportions of one-tenth of one part milk casein to onepart of said vegetable protein containing matter to ten parts i of milk casein to one part of. said vegetable protein containing matter.

14. As an article of manufacture,'an adhesive embodying milk casein and soya bean flour, which constituents are intermixed in the presence of water in the range of proportions of one-tenth of one art of milk casein to one part of soya bean our to ten arts of milk casein to one part of soya bean our.

15. As an article of manufacture, an adhesive embodying milk casein dispersed in an aqueous alkaline medium and heat treated a vegetable promanufacture, an ad- 7 cuts are intermixed in the range of-proportions of one to one to one to ten.

17. An adhesive material comprising casein as a substantial ingredient together with a substantial amount of protein-rich seed meal incorporated with an alkaline earth oxide and a water-soluble alkali metal salt, which salt is capable of reacting in the presence of water with such alkaline earth oxide, and water in sufficient amount to produce a mixture of spreadable consistency.

18. An adhesive material comprising the reaction products of a substantial amount of casein, a substantial amount of protein-rich seed meal, an alkaline earth hydroxide, an

' alkaline earth oxide our names this 3rd day of Au alkali metalcom and of alkaline reaction, and water in cient amount to produce a mixture of s readable consistency. a

19; An ad es'ive material comprising the reaction products of a substantial amount of casein, a substantial amount of rote1nrich seed nieal an'alkaline earth by an alkali metal hydroxide, and water in mificient amount to produce a mixture of spreadable consistency.

20. An adhesive containing the reaction.

roducts of casein, soya bean meal and an alaline earth oxide together with a water-soluble alkali metal salt which can react with alkali in the resenee of water to form caustic alkali an a preci itate, the said salt and ing in amounts sufficient for the reaction roducts and water to dissolve the casein an the proteids in the soya bean meal, 'and water in sufficient amount to form an adhesive of the foregoing in dients.

1. An adhesive material comprising the reaction products of a substantial amount of casein, a substantial amount of soya bean meal, an alkaline earth hydroxide, an alkali metal compound of alkaline reaction, and water in sufiicient amount to produce a mixture of spreadable consistency.

22. An adhesive material comprising the reaction products of a substantial amount of casein, a substantial amount of soya bean meal an alkalineearth hydroxide, an alkali metal hydroxide, and water in suflicient amount to produce a mixture of ,spreadable consistency.

In witness whereof, we hereunto subscribe st, 1925. HARRY P. ANKS. GLENN DAVIDSON".

xide, 

